Electronic device accessories formed from intertwined fibers

ABSTRACT

Fibers may be intertwined to form structures for electronic devices and other parts. Fibers may be intertwined using computer-controlled braiding, weaving, and knitting equipment. Binder materials may be selectively incorporated into the intertwined fibers. By controlling the properties of the intertwined fibers and the patterns of incorporated binder, structures can be formed that include antenna windows, sound-transparent and sound-blocking structures, structures that have integral rigid and flexible portions, and tubes with seamless forked portions. Fiber-based structures such as these may be used to form cables and other parts of headphones or other electronic device accessories, housings for electronic devices such as housings for portable computers, and other structures.

This application is a continuation of patent application Ser. No.15/476,793, filed Mar. 31, 2017, now U.S. Pat. No. 10,681,447, which isa continuation of patent application Ser. No. 12/637,355, filed Dec. 14,2009, now U.S. Pat. No. 9,628,890, which claims the benefit ofprovisional patent application No. 61/185,934, filed Jun. 10, 2009, allof which are hereby incorporated by reference herein in theirentireties.

BACKGROUND

This invention relates to structures formed from intertwined fibers, andmore particularly, to ways in which to form structures for electronicdevices from intertwined fibers.

Modern weaving, braiding, and knitting equipment can be used to createstructures that would be difficult or impossible to implement usingother fabrication technologies. For example, woven carbon fiber sheetsmay be used to form housing structures for electronic devices that arelighter and stronger than housing structures formed from othermaterials. Flexible cable sheaths may be formed using fiber braidingtools. Many medical devices are formed from fibers. For example,bifurcated vascular grafts and other cardiovascular devices may beformed from fibers.

SUMMARY

Intertwined fibers may be used in forming sheaths for cables, parts ofaccessories such as headsets, and other structures.

Fiber intertwining equipment such as tools for weaving, braiding, andknitting may be used to intertwine fibers. The fibers that areintertwined with this equipment may include polymer fibers, metalfibers, insulator-coated metal fibers, glass fibers, or other suitablefibers. Once intertwined, a binder such as epoxy or other suitablematrix may foe incorporated into the intertwined structure and cured.

Parameters that may be varied during the fabrication process include thenumber of fibers that are incorporated into a particular region of thestructure, the spacing between fibers, fiber type, binder type, binderlocation, etc. By selectively varying these factors, structures can beformed in which different regions of the structures have differentflexibilities, different densities (e.g., to adjust audio transparency,moisture penetration, etc.), different conductivities, etc. Shapes thatmay be formed using the intertwining equipment include forkingstructures (e.g., bifurcated structures), tubular structures of variablediameter, structures that have potentially complex compound curves, etc.

Further features of the invention, its nature and various advantageswill be more apparent from the accompanying drawings and the followingdetailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of illustrative fabrication equipment thatmay be used to fabricate structures with intertwined fibers inaccordance with an embodiment of the present invention.

FIG. 2 is a graph showing how parameters such as intertwining parametersand binder incorporation parameters may be varied as a function ofposition within a structure when fabricating the structure in accordancewith an embodiment of the present invention.

FIG. 3 is a side view of an illustrative structure showing how thenumber of fibers per unit area may be varied as a function of positionin accordance with an embodiment of the present invention.

FIG. 4 is a side view of an illustrative structure showing how the typeof fiber that is used may be varied as a function of position inaccordance with an embodiment of the present invention.

FIGS. 5, 6, and 7 are side views of illustrative binder incorporationpatterns that may be used when forming structures in accordance with anembodiment of the present invention.

FIG. 8 is a view of an illustrative tubular structure with a diameterthat has been varied during a fiber intertwining process in accordancewith an embodiment of the present invention.

FIG. 9 is a perspective view of an illustrative electronic device havinghousing with compound curves that have been formed by intertwiningfibers in accordance with an embodiment of the present invention.

FIG. 10 is a cross-sectional side view of an illustrative electronicdevice having compound housing curves that have been formed byintertwining fibers and that contains electronic components and adisplay screen in accordance with an embodiment of the presentinvention.

FIG. 11 is a rear view of an electronic device of the type shown in FIG.10 in accordance with an embodiment of the present invention.

FIG. 12 is a cross-sectional side view of an illustrative structurehaving a layer of intertwined fibers that have been used to form acosmetic cover layer and a fiber sheet that has been used to implement astructural support member in accordance with an embodiment of thepresent invention.

FIG. 13 is a top view of an illustrative fiber sheet of the type shownin FIG. 12 showing portions where material may be removed to help thefiber sheet accommodate a compound curve shape in accordance with anembodiment of the present invention.

FIG. 14 is a cross-sectional side view of an illustrative structure inwhich an inner support structure such as a solid support or a skeletalframe has been covered with a layer of fiber that has been intertwinedto accommodate a compound curve shape in accordance with an embodimentof the present invention.

FIG. 15 is a perspective view of an illustrative electronic device thatmay be formed using intertwined fiber in accordance with an embodimentof the present invention.

FIG. 16 is a perspective view of a forked (bifurcated) tubular structureformed with intertwining equipment in accordance with an embodiment ofthe present invention.

FIG. 17 is a cross-sectional view of a tubular structure such as a cablefor an electronic device in accordance with an embodiment of the presentinvention.

FIG. 18 is a cross-sectional side view of illustrative resin transfermold equipment that may be used to selectively incorporate binder intointertwined fibers in accordance with an embodiment of the presentinvention.

FIG. 19 is a top view of illustrative manufacturing equipment that maybe used to incorporate binder into a tubular structure in accordancewith an embodiment of the present invention.

FIG. 20 is a view showing how a headset cables may be formed by cuttinglengths of tube from a continuous tube of intertwined fiber havingbifurcated sections in accordance with an embodiment of the presentinvention.

FIG. 21 is a cross-sectional view of an illustrative switch formed fromintertwined conductive fibers in accordance with an embodiment of thepresent invention.

FIG. 22 is a perspective view of a tube of intertwined fibers having aconductive electrode portion for use in a switch or other structure inaccordance with the present invention.

FIG. 23 is a cross-sectional view of an illustrative switch formed froma fiber tube with multiple branches with conductive fibers andinsulating branch separator members in accordance with the presentinvention.

FIG. 24 is a side view of an illustrative fiber earbud structure havingportions that are more dense and that pass relatively small amounts ofsound and having portions that are less dense and that pass relativelylarge amounts of sound in accordance with an embodiment of the presentinvention.

FIG. 25 is a side view of an illustrative audio connector such as a 3.5mm audio plug showing how different parts of an associated sheath tubemay be provided with different amounts of rigidity in accordance with anembodiment of the present invention.

FIG. 26 is a cross-sectional side view of an illustrative audio plug andassociated cable sheath that may be formed of intertwined fibers inaccordance with an embodiment of the present invention.

FIG. 27 is a side view of an illustrative audio plug having a fibercable into which binder has been selectively incorporated to adjustcable flexibility along the length of the cable in accordance with anembodiment of the present invention.

FIG. 28 is a perspective view of an audio plug and fiber cable showinghow binder may be incorporated into the cable in a pattern that isradially asymmetric to gradually adjust cable flexibility in accordancewith an embodiment of the present invention.

FIG. 29 is a perspective view of an illustrative complex structure ofthe type that may be formed in an electronic device structure usingfiber intertwining and binder incorporation equipment in accordance withan embodiment of the present invention.

FIG. 30 is a perspective view of a fiber-based structure such as acomputer housing or a protective detachable case for an electronicdevice that may foe provided with a flexible hinge portion and rigidupper and lower planar portions in accordance with an embodiment of thepresent invention.

FIG. 31 shows how a fiber-based structure may be provided with aflexible pocket portion and a rigid planar portion in accordance with anembodiment of the present invention.

FIG. 32 is a perspective view of an illustrative electronic devicehaving a housing formed of fibers with different properties in differentregions to form, a radio-frequency (RF) antenna window in accordancewith an embodiment of the present invention.

FIG. 33 is a cross-sectional side view of an illustrative electronicdevice of the type shown in FIG. 32 showing how an antenna andtransceiver circuitry may be mounted within the device in accordancewith an embodiment of the present invention.

FIG. 34 is a flow chart of illustrative steps involved in formingfiber-based structures with selectively incorporated binder inaccordance with embodiments of the present invention.

FIG. 35A is a cross-sectional view of an illustrative monofilament fiberthat may be used in forming fiber-based structures in accordance with anembodiment of the present invention.

FIG. 35B is a cross-sectional view of an illustrative multifilamentfiber that may be used in forming fiber-based structures in accordancewith an embodiment of the present invention.

FIG. 35C is a cross-sectional view of an illustrative monofilament fiberformed from a composite structure containing multiple materials that maybe used in forming fiber-based structures in accordance with anembodiment of the present invention.

FIG. 35D is a cross-sectional view of an illustrative multifilamentfiber having filaments formed from different types of materials that maybe used in forming fiber-based structures in accordance with anembodiment of the present invention.

FIG. 35E is a cross-sectional view of an illustrative multifilamentfiber formed of composite fibers in accordance with embodiments of thepresent invention.

FIG. 36A is a cross-sectional view of a fiber-based cable containinginsulated wires and monofilament fibers in accordance with an embodimentof the present invention.

FIG. 36B is a cross-sectional view of a fiber-based cable containinginsulated wires and multifilament fibers in accordance with anembodiment of the present invention.

FIG. 37 is a cross-sectional view of a fiber-based cable containinginsulated wires and more than one type of fiber in accordance with anembodiment of the present invention.

FIG. 38 is a perspective view of a tube-shaped bifurcated fiber-basedcable in accordance with an embodiment of the present invention.

FIG. 39A is a perspective view of a ribbon-shaped fiber-based cablehaving a converging bifurcation in accordance with an embodiment of thepresent invention.

FIG. 39B shows cross-sectional side views of a cable in accordance withan embodiment of the present invention.

FIG. 40 is a perspective view of a ribbon-shaped fiber-based cablehaving an overlapping bifurcation in accordance with an embodiment ofthe present invention.

FIG. 41A is a cross-sectional view of an illustrative ribbon-shapedfiber-based cable having a rectangular profile in accordance with anembodiment of the present invention.

FIG. 41B is a cross-sectional view of an illustrative ribbon-shapedfiber-based cable having a rectangular profile with rounded corners inaccordance with an embodiment of the present invention.

FIG. 41C is a cross-sectional view of an illustrative ribbon-shapedfiber-based cable having a flattened oval profile in accordance with anembodiment of the present invention.

FIG. 41D is a cross-sectional view of an illustrative ribbon-shapedfiber-based cable having an oval profile in accordance with anembodiment of the present invention.

FIG. 42 is a perspective view of an illustrative headset formed fromfiber-based cables that has a switch located on one arm in accordancewith an embodiment of the present invention.

FIG. 43A is a perspective view of a segment of an illustrativefiber-based cable that may be used in an accessory in accordance with anembodiment of the present invention.

FIG. 43B is a cross-sectional view of an illustrative fiber-based cableshowing how conductive wires may be located in the central core of thecable in portions of the cable such as at cross-sectional line X-X ofFIG. 43A in accordance with an embodiment of the present invention.

FIG. 43C is a cross-sectional view of an illustrative fiber-based cableshowing how conductive wires may be selectively brought to the surfaceof the cable to form part of a switch structure in accordance with anembodiment of the present invention.

FIG. 43D is a cross-sectional view of an illustrative fiber-based cableshowing how conductive wires may be located in the central core of thecable in portions of the cable such as at cross-sectional line Z-Z ofFIG. 43A in accordance with an embodiment of the present invention.

FIG. 44A is a perspective view of a portion of a fiber-based cablehaving a button assembly in accordance with an embodiment of the presentinvention.

FIG. 44B is a cross-sectional view of a cable of the type shown in FIG.44A taken along cross-sectional line X-X of FIG. 44A in accordance withan embodiment of the present invention.

FIG. 44C is a cross-sectional view of a cable of the type shown in FIG.44A taken along cross-sectional line Y-Y of FIG. 44A through the buttonassembly portion of the cable of FIG. 44A in accordance with anembodiment of the present invention.

FIG. 44D is a cross-sectional view of a cable of the type shown in FIG.44A taken along cross-sectional line Z-Z of FIG. 44A in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION

A schematic diagram of illustrative fabrication equipment that may beused to fabricate structures with intertwined fibers in accordance withan embodiment of the present invention is shown in FIG. 1 . Fabricationequipment may be used to form fiber-based structures for any suitabledevice. Examples in which fabrication equipment 10 is used to form partsof electronic devices such as electronic device housings, cable sheathsfor headsets, electrical connectors, and other electrical equipment aresometimes described herein as an example. In general, however,fabrication equipment 10 may be used to form any suitable parts (e.g.,parts for medical application, for industrial equipment, for mechanicalstructures with no electrical components, etc.).

As shown in FIG. 1 , fabrication equipment 10 may be provided withfibers from fiber sources 12. Fiber sources 12 may provide fibers of anysuitable type. Examples of fibers include metal fibers (e.g., strands ofsteel or copper), glass fibers (e.g., fiber-optic fibers that caninternally convey light through total internal reflection), plasticfibers, etc. Some fibers may exhibit high strength (e.g., polymers suchas aramid fibers). Other fibers such as nylon may offer good abrasionresistance (e.g., by exhibiting high performance on a Tabor test). Yetother fibers may be highly flexible (e.g., to stretch without exhibitingplastic deformation). The fibers provided by sources 12 may be magneticfibers, conducting fibers, insulating fibers, or fibers with othermaterial properties.

Fibers may be relatively thin (e.g., less than 20 microns or less than 5microns in diameter—i.e., carbon nanotubes or carbon fiber) or may bethicker (e.g., metal wire). The fibers provided by sources 12 may beformed from twisted bundles of smaller fibers (sometimes referred to asfilaments) or may be provided from sources 12 as unitary fibers of asingle untwisted material. Regardless of their individual makeup (i.e.whether thick, thin, or twisted or otherwise formed from smallerfibers), the strands of material from fiber sources 12 are referred toherein as fibers. The fiber from sources 12 may also sometimes bereferred to as cords, threads, ropes, yarns, filaments, strings, twines,etc.

Intertwining tool(s) 14 may be based on any suitable fiber intertwiningtechnology. For example, intertwining equipment 14 may includecomputer-controlled weaving tools, computer-controlled braiding tools(e.g., for forming tubular structures), and/or computer-controlledknitting equipment (e.g., three-dimensional knitting tools capable ofproducing intertwining fiber structures with bifurcations/compoundcurves, and other such complex shapes). These tools are sometimesreferred to collectively herein as intertwining tool(s) 14.

Tools 14 form intertwined fiber structures. Matrix incorporationtools(s) 16 may be used to incorporate binder material into theintertwined fiber (e.g., to provide these structures with rigidity orother suitable properties). The binder, which is sometimes referred toas a matrix, may be formed from epoxy or other suitable materials. Thesematerials may sometimes be categorized as thermoset materials (e.g.,materials such as epoxy that are formed from a resin that cannot bereflowed upon reheating) and thermoplastics (e.g., materials such asacrylonitrile butadiene styrene, polycarbonate, and ABS/PC blends thatare reheatable). Both thermoset materials and thermoplastics andcombinations of thermoset materials and thermoplastic materials may beused as binders if desired.

Tools 16 may include molds, spraying equipment, and other suitableequipment for incorporating binder into portions of the intertwinedfibers produced by intertwining equipment 14. Tools 16 may, if desired,include computer-controlled equipment and/or manually operated equipmentthat can selectively incorporate binder into different portions of aworkpiece in different amounts. For example, when it is desired tostiffen a fiber structure, more resin can be incorporated into theintertwined fiber, whereas less resin can be incorporated into theintertwined fiber when a flexible structure is being formed. Differentportions of the same structure can be formed with differentflexibilities in this way. Following curing (e.g., using heat orultraviolet light, the binder will stiffen and harden). The resultingstructure (called finished part 20 in FIG. 1 ) can be used in a computerstructure, a structure for other electrical equipment, etc.

A graph showing how parameters such as intertwining parameters andbinder incorporation parameters may be varied as a function of positionwithin a structure when fabricating the structure is shown in FIG. 2 .The horizontal axis in the graph of FIG. 2 represents position within afiber-based structure (e.g., length along a cable or lateral distanceacross a planar surface). The vertical axis represents the magnitude ofthe parameter that is being varied. As the lines of the graph of FIG. 2indicate, parameters can be varied smoothly and continuously,discretely, in an increasing fashion, decreasing, periodically, etc.Examples of parameters that can be varied according to the lines of thegraph of FIG. 2 include the number of fibers in a given area, the sizeof the individual fibers, the spacing between adjacent fibers (porosityor fiber density), the type of filaments being used (e.g., the amountwhich a fiber or collection of fibers is insulating, abrasion-resistant,conducting, strong, magnetic, etc.), and the amount and/or type ofbinder being incorporated.

FIG. 3 is a side view of an illustrative structure such as a tube orplanar patch of intertwined fiber showing how the number of fibers perunit area may be varied as a function of position. In region 22 thereare more fibers per unit area than in region 24. The portion of thestructure in region 24 will tend to be weaker, more porous, andtherefore transparent to moisture and sound, lighter, and more flexiblethan the portion of the structure in region 22.

As shown in FIG. 4 , structure 26 may have two or more different typesof fibers such as fibers 28 and fibers 30. These fibers may havedifferent properties. In the FIG. 4 example, there are more of fibers 28in region 32 than fibers 30. In region 34, however, fibers 30 are moreprevalent than fibers 28. This type of spatial variation of fiber typeallows the properties of structure 26 to be spatially adjusted duringfabrication with equipment 10.

FIGS. 5, 6, and 7 are examples of structures in which binder has beenincorporated in different patterns. In structure 36 of FIG. 5 ,intertwined fiber portions 38 may be formed without binder, whereasportions 40 may include binder. Structure 36 may be a fiber tube or aplanar fiber-based structures (examples). In structure 42 of FIG. 6 ,there is only a single relatively large portion of binder (region 44),while regions 46 are free of binder. In structure 48 of FIG. 7 , regions50 are binder-free, whereas regions 52 incorporate binder in differentpatterns.

Equipment 10 can be used to form fiber-based structures of variousshapes (e.g., tubes, planar members such as housing surfaces, spheres orparts of spheres, shapes with compound curves, cylinders or partialcylinders, cubes, tubes with bifurcations or regions of three or moreforked branches, combinations of these shapes, etc.). FIG. 8 shows howequipment 10 can form a tube or other structure 58 with a diameter Dthat is narrower in some regions (e.g., regions 54) than in otherregions (e.g., region 56).

A perspective view of an illustrative electronic device having a housingwith compound curves is shown in FIG. 9 . As shown in FIG. 9 , device 60may have a housing or other structure that has a planar rear surfaceportion such as portion 64. Device 60 may also have four corner portions62. Each corner portion 62 has compound curves. These curves may bedifficult or impossible to form from conventional woven-fiber sheets.

With equipment 10 of FIG. 1 , three-dimensional (3D) knitting equipmentor other intertwining tools 14 can be used to form a fiber-basedstructure (e.g., a housing or covering) that conforms to both the planarrear surface 64 and compound curve corners 62 of structure 60.

A cross-sectional side view of device 60 of FIG. 9 taken along line 66of FIG. 9 and viewed in direction 68 is shown in FIG. 10 . As shown inFIG. 10 , device 10 may have curved sidewalls 70, a display or otherfront-mounted component 74, and internal electronic devices 72 (e.g.,processor and memory circuitry). A rear view of device 60 is shown inFIG. 11 , illustrating part of the curved shapes of corners 62 that canbe covered smoothly without wrinkles or seams using the knit fiberproduced by equipment 10.

The ability of equipment 10 to produce thin layers of intertwined fiberthat conform to complex non-planar shapes can be used to create acosmetic cover layer with compound curves. As shown in FIG. 12 , devicehousing 80 may have an inner layer 78 that is formed from a planar sheetof fiber with cut-away portions to accommodate compound curve housingshapes (e.g., corners 62 of FIG. 9 ). Layer 76 may be a conformalcosmetic cover layer formed using equipment 10. Layers 76 and/or layer78 may be impregnated with binder using a matrix incorporation tool.

FIG. 13 is a top view of a planar layer such as layer 78 that hasremoved portions 82 to accommodate compound curve shapes (e.g., housingcorners). This process leaves unsightly seams that are hidden bycosmetic layer 76 (FIG. 12 ).

FIG. 14 is a cross-sectional side view of device 80 showing how layer 76may conformally cover an inner support structure (i.e., structure 84)and how device 80 may have a display module or other component 86mounted to its front surface. Structure 84 may be solid, may be hollow(e.g., as in a frame or skeletal support), may include components, etc.

An example of an electronic device accessory that may be formed fromintertwined fiber structures is a pair of audio headphones. Anillustrative headset is shown in FIG. 15 . As shown in FIG. 15 , headset88 may include a main cable portion 92. Cable 92 may be formed fromintertwined fibers and may have portions formed from different types andamounts of fibers and different patterns and amounts of binder (asexamples). Earbuds 90 (i.e., earbuds that each contains one or morespeakers) may be mounted at the ends of the right and left branches ofcable 92. In region 94, cable 92 may have a bifurcation (forked region).Feature 96 may be an enclosure for a switch, microphone, etc. The end ofcable 92 may be terminated by audio connector (plug) 98. Connector 93may be, for example, a 3.5 mm audio plug that mates with a corresponding3.5 mm audio jack in a media player, cellular telephone, portablecomputer, or other electronic device.

FIG. 16 shows how intertwining tool 14 may, if desired, form Y-junction94 of cable 92 without visible seams. A cross-sectional view of cable 92is shown in FIG. 17 . As shown in FIG. 17 , cable 92 may have a tubularsheath such as sheath 100 that surrounds one, two, or more than twowires. In the FIG. 17 example, there are two conductive wire bundleswithin sheath 100. Wire bundle 102 may be formed from a first set ofmetal fibers and wire bundle 104 may be formed from a second set of wirebundles. The individual wires in bundles 102 and 104 may be coated witha thin layer of insulator (if desired). Sheath 100 may be formed from afiber with sufficient strength to resist damage during use by a user andsufficient flexibility to allow cable 92 to flex. If desired, regionssuch as Y-junction region 94 and portions of device 88 near earbuds 90and plug 98 may be provided with stronger fibers and more binder tostrengthen these regions.

Structure 96 may also be strengthened in this way. As an example,structure 96 may be impregnated with binder, whereas most of the rest ofcable 92 may be left binder-free. FIG. 18 shows how a resin transfermolding tool such as tool 106 may be used to selectively incorporatebinder 110 into region 96 of cable 92 (e.g., by introducing binder 110into the interior of tool 106 through opening 108).

As shown in FIG. 19 , cable 92 may be rotated in direction 124 aboutlongitudinal axis 126 while binder 110 is being sprayed onto cable 92from spraying tool 114. Binder 110 may be cured using ultraviolet light122 from ultraviolet light source 120. Shield 116 may prevent binder 110from striking source 120 and may prevent light. 122 from curing binder110 at the exit of nozzle 128.

Equipment 10 may produce cable 92 using a continuous process. As shownin FIG. 20 , equipment 10 may produce a cable shape that periodicallyforks to form two separate branches and then fuses so that the twobranches form a single tubular structure. With this type of arrangement,post processing tools 18 of FIG. 1 may be used to cut cable 92 along cutlines 130.

As shown in FIG. 21 , cable 92 may be provided with conductive fiberssuch as fibers 132 and 134. This type of configuration may be producedwhen it is desired to form a switch in structure 96. As shown in FIG. 21, conductive fibers 132 and conductive fibers 134 in structure 96 may beseparated by gap region 136. Region 136 may be filled with air (as anexample). When a user squeezes outer edges inwardly in directions 140,opposing inner portions 142 of conductors 132 and 134 can meet, therebyclosing the switch.

Conductive fibers on cable 92 may be used to form a capacitor electrode(e.g., as part of a switch based on a capacitive sensor). This type ofconfiguration is illustrated by conductive fiber band 144 on cable 92 inFIG. 22 .

In the example of FIG. 23 , switch 96 has been formed from opposingmetal conductor portions 132 and 134 (each of which may be connected toa respective cable wire such as wires formed from wire bundles 102 and104). Cable 92 may have two branches that rejoin each other on eitherend of switch structure 96. In the center of structure 96, outwardbiasing members 146 (e.g., air filled balloons or spring-filled members)may be used to bias switch contacts 132 and 134 away from each other inoutward directions 143 so that switch 96 is off when not compressedinwardly by a user.

A side view of an illustrative fiber-based earbud and associated cableis shown in FIG. 24 . As shown in FIG. 24 , earbud 90 may have regions150 and 152. Region 150 may be more porous than region 152 and may bemore (or less) flexible than region 152. The increased porosity ofregion 150 may make region 150 transparent to audio, so that sound frominternal speaker drivers may pass through regions 150 unimpeded. Regions150 may have fewer and less densely intertwined fibers than region 152and may incorporate less binder than region 152 or no binder. It may bedesirable to make region 152 less porous (e.g., to block sound, toincrease rigidity or durability, etc.). Accordingly, more binder may beincorporated into region 152 than in region 150 and/or fibers may bemore densely intertwined. In addition to increasing the fiber densityand/or binder quantity in region 152, different (e.g., denser, thicker,etc.) fibers may be used in region 152. Cable 92 in region 154 may beformed of flexible fibers (e.g., with little or no binder). If desired,some of cable 92 near region 152 may be provided with stronger fibers,more fibers, more binder for rigidity and strength, etc.

As shown in FIG. 25 , audio plug 98 (or other electrical connectors) maybe provided with a flexible cable portion 92 and a rigid inner strainrelief structure 158. Metal plug structure 160 may be connected to wireswithin cable 92. In region 156, binder may be incorporated into thefibers of cable 92 to increase strength and rigidity. If desired, cable92 may also be provided with an increased number of strong fibers inregion 156 and/or may be provided with a higher fiber density to furtherincrease strength. These types of structural features may be used forany suitable electrical connector. The use of an audio connector in FIG.25 is merely an example.

FIG. 26 shows how cable 92 may form a conformal sheath over support(strain-relief) structure 158 and wires 102 and 104.

The flexibility of cable 92 can be adjusted along its length byselectively incorporating binder in appropriate areas. This type ofarrangement is shown in FIG. 27 . In the example of FIG. 27 , connector98 may have a metal multi-contact portion such as portion 160 (e.g., athree-contact or four-contact audio plug). Region 162 of connector 98may be completely filled with binder. Only some portions (e.g., rings168) of region 164 are provided with binder (in this example), so cable92 will be more flexible in region 164 than in region 162. In region170, there is no binder in the fibers of cable 92, so cable 92 hasmaximum flexibility in region 170.

Another suitable arrangement for connector 98 is shown in FIG. 23 . Inthe example of FIG. 23 , cable 92 has no binder in region 178 and istherefore flexible in this region. In region 176, a non-radiallysymmetric pattern of binder 172 is used to provide a decreasedflexibility. Region 174 has more binder than region 172 and is thereforerigid and structurally strong. This type of configuration allows thebinder pattern in region 176 to serve as a moderate-flex interfacebetween rigid region 174 and flexible region 178.

FIG. 29 shows how equipment 10 may be used to form complex shapes forpart 20 such as hook 180 with hole 182. The fiber in hook 180 may beformed of stronger material than the fiber elsewhere in the structure.Part 20 may be formed as an integral portion of an electronic devicehousing (as an example)

As shown in FIG. 30 , equipment 10 may form structures such as structure184 that have rigid planar portions such as rigid planar portions 186and 188 and flexible hinge portions such as flexible hinge 190. Thistype of arrangement may be provided by incorporating binder intoportions 186 and 188, but not into hinge 190. Structure 184 may be usedfor a portable computer housing, a folio-style case for a detachableelectronic device such as a media player or cellular telephone, etc.

As shown in FIG. 31 , a fiber-based case or other fiber-based structure192 may be formed from a rigid binder-filled planer portion 194 and aflexible binder-free portion 196. Portion 196 may serve as a flexiblepocket that holds a cellular telephone or music player. Portion 194 maybe provided with a matching front face if desired.

Some parts that are formed from fiber-based structures may be used forelectronic device housings or other applications in which at least aportion of the structure is adjacent to an antenna. In situations suchas these, it may be desirable to incorporate one or more antenna windowsinto the part. For example, in an electronic device housing that isformed from conductive fibers, an antenna window that is transparent toradio-frequency antenna signals can be formed over an antenna within theelectronic device housing. The antenna window 30 can be formed byincorporating a solid dielectric window in the housing and by attachingthe conductive fibers to the solid window (e.g., using epoxy or otheradhesive). Antenna window structures can also be formed by usingequipment 10 to form an integral fiber-based antenna window structurewithin part of the electronic device housing. The antenna windowstructure may be formed from a fiber that contains primarily polymer,glass, or other dielectric. Because this material is nonconducting, theantenna window structure will be able to pass radio-frequency signalswithout interference from the fibers in the window.

An illustrative fiber-based structure with an antenna window is shown inFIG. 32 . Structure 200 of FIG. 32 may be, for example, a housing for anelectronic device such as a media player, cellular telephone, portablecomputer, or other electronic device. Structure 200 may be formed usingequipment 10. For example, structure 200 may include corner portionsthat have compound shapes that have been created using intertwining tool14 (e.g., 3D knitting equipment). In regions 198, housing walls can beformed from insulating or conductive materials or combinations ofinsulating and conductive materials (e.g., carbon fibers, polymers,steel filaments, etc.). The materials in regions 198 may includeconductors (nondielectrics) and may therefore block radio-frequencywireless signals. Equipment 10 can use dielectric fiber when forming theintertwined fibers of antenna window 202, thereby ensuring that thematerial in window 202 will be transparent to antenna signals.

A cross-sectional side view of structure 200 of FIG. 32 taken along line201 is shown in FIG. 33 . As shown in FIG. 33 , structure 200 may havehousing walls 198 that are formed from intertwined fibers and associatedbinder. In region 202, an antenna window is formed by using dielectricfibers and binder that are transparent to wireless radio-frequencysignals. This allows radio-frequency signals 212 to pass through window202 during wireless transmission and reception operations with antenna206. Antenna 206, which may be a single band antenna or a multi-bandantenna and which may include one or more individual antenna structures,may be coupled to radio-frequency transceiver circuitry 210 on printedcircuit board 204 using transmission line path 208.

Illustrative steps involved in forming fiber-based structures usingequipment 10 of FIG. 1 are shown in FIG. 34 . At step 214, equipment 10may be provided with one or more different sources of fibers (e.g.,fiber sources 12 of FIG. 1 ). Fibers may be used that provide suitableamounts of strength, stretchability, flexibility, abrasion resistance,insulation, conductivity, color, weight, magnetism, etc. Some of thefibers may be formed from metals such as ferrous metals. Other fibersmay be formed from polymers or glasses. There may be one, two, three, ormore than three different types of fiber sources available to a givenintertwining tool 14. Each fiber may have a different property and maybe incorporated into a workpiece in an accurately controlled percentage.This allows tools 14 to form structures that have portions withdifferent properties.

At step 216, tools 14 may be used to form fiber-based structures ofappropriate shapes and sizes. Different types of tools may be used fordifferent types of operations. For example, a computer-controlledbraiding machine may be used to form a continuous or semi-continuousfiber-based tube for a headset cable sheath, a weaving tool may be usedto form housing sidewalls for a portable computer with an integralantenna window or a flexible hinge portion, and a 3D knitting tool maybe used to form housing shapes with compound curves for a cosmetic orstructural housing surface. These tools may each be used to formseparate parts that are assembled together by hand or by automatedassembly tools or may be used to form unitary structures that arecomplete without the addition of further fiber-based parts.

During the operations of step 218, matrix incorporation equipment 16 maybe used to selectively incorporate binder into the intertwined fibersthat were produced during the operations of step 214. Binder may beincorporated in patterns that provide controlled amounts of flexibility.For example, binder patterns may include rings of the same shape ordifferent shapes (e.g., rings of varying width of other patterns thatprovide a smooth transition in the amount flexibility at various pointsalong the length of a tube or other elongated structure). Binderpatterns may also include solid regions (e.g., for forming rigid planarstructures such as housing walls for a portable computer, handheldelectronic device, or other structure). Other regions of a structure maybe provided with little or no binder (e.g., in a hinge structure, cable,or pocket where maximum flexibility is desired or in an earbud speakerport or computer housing speaker port where audio transparency isdesired).

After incorporating desired patterns of binder into the intertwinedfiber structures, additional processing steps may toe performed duringthe operations of step 220. These operations may include, for example,assembling a headset by cutting headset parts from a continuous streamof parts, adding a cosmetic cover to a structural housing member, usingadhesive or other fasteners to connect separate fiber-based structuresto each other or to parts that do not include fibers, etc.

If desired, the steps of FIG. 34 may be repeated and/or performed indifferent orders. For example, it may be desirable to assemble two ormore intertwined fiber parts before matrix incorporation operations areperformed at step 218. It may also be desirable to build up complexstructures by using a series of incremental operations. During each suchincremental step, a layer of fiber-based material may be added to aworkpiece and additional binder may be incorporated and cured. Anincremental approach such as this may be used for part of a fiber-basedstructure while other parts of the structure are formed using a singleintertwining operation and a single binder incorporation operation (asexamples).

The fibers that are used for constructing fiber-based cables and otherfiber-based structures may be formed from materials such as nylon,polyester, polypropylene, para-aramid (long-chain polyamide) syntheticfibers such as KEVLAR® fiber, other polymers, glass, metals such assteel, or ether suitable material. If desired, fibers may be formed froma super-elastic shape memory alloy such as nickel titanium (sometimesreferred to as nitinol). Combinations of these materials may also beused.

Fiber materials may be chosen so as to provide device housings, cables,and other structures that are formed from intertwined fibers withdesired properties. For example, materials may be selected that arestrong, exhibit good abrasion resistance, and are not difficult to color(e.g., by incorporating pigments). It may be desirable to choosematerials based on their conductive (or non-conductive) or magneticproperties. It may also be desirable to use cost-effective materials.Materials such as nylon (polyamides) and polyester may be receptive tocoloring additives. A material such as a para-aramid synthetic polymermay be strong, but may exhibit relatively poor abrasion resistance. Itmay therefore be desirable to incorporate para-aramid synthetic fibersinto cables that also incorporate other fibers (e.g., fibers with goodabrasion resistance such as an appropriate nylon). A fiber-based cableformed from a material such as steel may exhibit magnetic properties.For example, a steel-based cable may be magnetized. Magnetized cablesmay be magnetically attracted to themselves, thereby facilitating cablemanagement. Magnetic cables may also be held in place using magnets(e.g., when the cables are being stored between uses). Fiber-basedcables and other structure may be provided with these magneticproperties by incorporating steel fibers into at least part of thestructures. It may be desirable to form individual fibers from acomposite of materials to take advantage of the properties of differentmaterials. Fibers may also be formed from multiple filaments.

An illustrative fiber that is formed from single filament (i.e., amonofilament fiber structure) is shown in FIG. 35A. In particular, FIG.35A shows a cross-sectional view of monofilament fiber 222. Fiber 222may be, for example, a monofilament of nylon or other suitable material.Fiber 222 may have any suitable diameter (e.g., 0.5 mm or less, 0.2 mmor less, 0.1 mm or less, 0.05 mm or less, 0.02 mm or less, 0.01 mm orless, etc.).

A cross-sectional view of an illustrative fiber that is formed frommultiple filaments is shown in FIG. 35B. As shown in FIG. 35B,multifilament fiber 224 may be formed from numerous individual filaments226. Filaments 226 may be, for example, formed from nylon, polyester, orother suitable materials. Filaments 226 may be intertwined usingintertwining tool 14 (FIG. 1 ) or other suitable equipment to form fiber224.

FIG. 35C shows a cross-sectional view of a monofilament fiber (fiber228) that is formed from a composite of different materials. Compositefiber 228 is formed from materials that remain distinct within fiber 228so that some parts of fiber 228 are predominantly formed from a certainmaterial, whereas other parts of fiber 228 are predominantly formed fromanother material. In the example of FIG. 35C, fiber 228 is shown ashaving two distinct materials 230 and 232. In general, fiber 228 may beformed of any number of distinct materials (e.g. three or more differentmaterials, four or more materials, etc.). If desired, each of thematerials 230 and 232 may be in itself be formed from a mixture ofmaterials. Fiber 228 is shown segmented radially in the illustrativecross-section of FIG. 35C. In general, fiber 228 may be divided intomultiple different materials in any suitable fashion. For example,different materials may be formed in radially symmetric coatings (i.e.,different layers).

FIG. 35D shows a cross-sectional view of a multifilament fiber (fiber234) that has filaments 236 and 238 that are formed from differentmaterials. Fiber 234 may have any suitable proportion of filaments 236and 238. Fiber 234 is shown as having two types of filaments, although,in general, fiber 234 may have any number of types of filaments.Filaments 236 and 238 may be intertwined using intertwining tool 14 orother suitable equipment.

Another illustrative arrangement that may be used for forming amultifilament fiber is shown in the cross-sectional view of FIG. 35E. Asshown in FIG. 35E, multifilament fiber 240 may have filaments 242 thatare formed from a composite of materials. In the FIG. 35E example, eachfilament 242 is shown having radial segments of materials 244 and 246.In general, filament 242 may be formed of any number of distinctmaterials and filament 242 may be segmented in any suitable manner.Fiber 240 of FIG. 35E is shown as having only one type of compositefilament 242. If desired, fiber 242 may be formed of any number of typesof composite filaments or may be formed of a mixture of compositefilaments and unitary-material filaments (i.e., filaments that are notformed from a composite of multiple materials). Filaments 242 may bewound together like yarn to form fiber 240 using intertwining tool 14 orother suitable equipment.

Fiber-based cables may contain insulated wires. An arrangement of thistype is shown in the examples of FIGS. 36A and 36B. FIG. 36A shows across-sectional view of a fiber-based sheath formed from intertwinedmonofilament fibers 245. Fibers 245 may be intertwined in any suitablefashion and may be formed in one or more layers. For example, fibers 245may be woven such that some fibers 245 form a warp and other fibers 245form a weft. Fibers 245 may be knitted such that fibers 245 forminterlocking loops. Fibers 245 may also be braided. One or moreinsulated wires 247 may lie inside cable 242. Each insulated wire 247may have a conductive center 248 and a layer of insulation such asinsulation 250. Conductive center 248 may be formed from copper or othersuitable conductive material. Insulation 250 may be formed from plastic(as an example). Cable 242 is shown has having two insulated wires 247in the example of FIG. 36A. In general, cable 242 may have any suitablenumber of insulated wires 247. In FIG. 36A, insulated wires 247 areshown as being surrounded by one layer of fibers 245. In general,insulated wires 247 may be surrounded by any suitable number of fiberlayers.

FIG. 36B shows a cross-sectional view of a fiber-based cable 252 thathas a fiber-based sheath formed from multifilament fibers 254. Eachfiber 254 may have many filaments 256. Fibers 254 may be woven, knitted,braided, or otherwise intertwined using intertwining tool 14 or othersuitable equipment. Cable 252 may have insulated wires 247 that eachhave a conductive center 248 surrounded by insulation 250. Cable 252 ofFIG. 36B is shown as having two insulated wires 247. If desired, cable252 may have a different number of insulated wires 247 (e.g., three ormore wires 247, etc.). Cable 252 has a fiber-based sheath that is formedfrom one layer of multifilament fibers 254 although in general cable 252may have a fiber-based sheath that has any suitable thickness and anynumber of layers of 252. Cable 252 may have a fiber-based sheath that isformed from a mixture of monofilament and multifilament fibers. Cable252 may have a fiber-based sheath that has fibers of different materialsor fibers formed from composite materials.

FIG. 37 is a cross-sectional view of a fiber-based cable 258 that isformed from two types of fibers. Cable 258 has fibers 260 that may be,for example, nylon or another polymer. Fibers 262 may be a differentmaterial such as para-aramid, glass, steel, or other suitable material.Fibers 262 that are formed from strong materials such as para-aramidmaterials may add strength to cable 258.

Fibers 262 that formed from magnetic materials such as steel may addmagnetic properties to cable 258.

Fibers 262 may be monofilament or multifilament fibers. Fibers 262 mayalso be formed from composite materials. Fibers 260 and 262 may bewoven, knitted, braided, or intertwined in any other suitable fashion.The fiber-based sheath of cable 258 is shown as having a thickness oftwo fibers. In general, fiber-based sheaths for cables may have anysuitable thicknesses. Fibers 262 are shown in FIG. 37 as being part ofan inner layer of cable 258, but if desired, fibers 262 may also beformed as part of the outermost surface of cable 258. Cable 258 is shownas having two insulated wires 247 each having conductive center 248 andinsulation 250. This is merely illustrative. Fiber-based cables such ascable 258 may have any suitable number of insulated wires 247.

A seamless Y-junction (sometimes referred to as a bifurcation) may beformed in an accessory cable by forming the cable with intertwining tool14. As shown in FIG. 38 , for example, cable 264 may be formed with aseamless Y-junction such as junction 272. Fiber-based cable 264 in theexample of FIG. 38 has a round profile, so cable 264 has a cylindricaltube shape. Below Y-junction 272 (i.e., at the proximal end of aheadset, near its audio plug), cable 264 has only one branch 266. Branch266 may have a diameter D1. After the Y-junction (i.e., at the distalend of the headset near its speakers), cable 264 may have two branches268 and 270. Branch 268 may have a diameter D2 and branch 270 may have adiameter D3. Each of the diameters D2 and D3 may be less than diameterD1 of branch 266 or may be equal or greater than the diameter D1 ofbranch 266. Diameters D2 and D3 may, if desired, be equal.

In a typical arrangement, fiber-based cable 264 has fibers that areintertwined so that the number of fibers that are present at one end ofthe cable is substantially same as the number of fibers that are presentat another end of the cable. For example, branch 266 may contain N1fibers (i.e., N1 fibers would pass through a cross-section of branch266). Similarly, branch 268 may contain N2 fibers and branch 270 maycontain N3 fibers. The fibers of cable 264 may be intertwined in such away that the number of fibers that are present before the Y-junction isthe same as the number of fibers after the Y-junction, i.e., N1=N2+N3.Each of the fibers in branches 268 and 270 in this type of arrangementpasses through Y-junction 272 to branch 266. Each fiber that has one endin branch 266 has another end in either branch 268 or branch 270. Inarrangements in which electrically insulated wires are contained in thestructure, these wires typically pass uninterrupted from branch 266 tobranches 268 and 270, even if ail of the wires are not needed at thedistal ends of branches 268 and 270. This is because intertwining tool14 typically does not interrupt delivery of particular wires to thecable during the cable formation process (i.e., the cable formationprocess is substantially continuous as described in connection with theexample of FIG. 20 ).

The fibers of cable 264 may form a sheath. Insulated wires may becontained in the sheath. The number of insulated wires in branch 266 maybe equal to the number of wires in branch 268 plus the number of wiresin branch 270. Each wire that has one end in branch 266 may have anotherend in either branch 268 or branch 270. If cable 264 is a headphonecable, four wires may be present in branch 266, with two of the wirescontinuing into branch 268 and the other two wires continuing intobranch 270. Cables for accessories with additional electronic componentssuch as button assemblies and microphones may have more insulated wires(e.g., another two or four wires that extend from branch 266 to branch268).

A fiber-based cable may also have a flat, ribbon-like profile. This typeof fiber-based cable is shown as cable 274 in FIG. 33A. Cable 274 mayhave a rectangular or oblong cross-section. A Y-junction such asjunction 276 may be formed in cable 274. At one side of Y-junction 276(i.e., at the proximal end of a headset or other accessory), cable 274may have one branch 278. At another side of Y-junction 276 (i.e., at thedistal end of a headset or other accessory), cable 274 may have twobranches 280 and 282. The same number of fibers may be present beforeand after the Y-junction, e.g., the number of fibers in branch 278 maybe equal to the number of fibers in branches 280 and 282. Each ofbranches 280 and 282 may be thinner or have a smaller cross-section thansingle branch 278.

Y-junctions such as Y-junction 276 of FIG. 39A may sometimes be referredto as converging Y-junctions. Single branch 278 may have a width W1 anda thickness T1. At the other side of Y-junction 276, branches 280 and282 may each have a width W2 and a thickness 72. The thickness of cable274 may be substantially the same before and after the Y-junction, sothat T1=T2, as shown in FIG. 39B. Single branch 278 may have a width W1that is approximately twice the widths W2 of branches 280 and 282 (as anexample). For example, branch 278 may have a width W1 of 2 millimetersand a thickness T1 of 0.5 mm. Branches 280 and 282 may each have a widthW2 of 1 millimeter and a thickness T2 of 0.5 millimeters. Thesedimensions are merely illustrative. In general, cable 274 may have anysuitable dimensions. In the example of FIG. 39A, branches 280 and 282are shown as having the same cross-sectional dimensions, but, ifdesired, branches 280 and 282 may have different cross-sectionaldimensions.

A fiber-based cable with a ribbon-like profile may also have anoverlapping Y-junction, as shown in FIG. 40 . Fiber-based cable 286 inFIG. 40 has one branch 290 on one side of Y-junction 288 (i.e., at theproximal end of a pair of headphones) and two branches 292 and 294 onanother side of Y-junction 288 (i.e., at the distal end of theheadphones). Branches 292 and 294 may overlap slightly before uniting atY-junction 288. Ribbon-like cable 286 may have a rectangular or oblongcross-section. Single branch 290 may have a width W1 that is greaterthan a thickness T1. Branches 292 and 294 may have widths K2 that aregreater than thicknesses T2. Single branch 290 may have a width W1 thatis the approximately the same as widths W2 of branches 292 and 294.Single branch 290 may have a thickness T1 that is approximately twicethe thickness T2 of branches 292 and 294. For example, single branch 290may have a width of 1.5 millimeters and a thickness of 1.0 millimeters.Branches 292 and 294 may each have widths W2 of 1.5 millimeters andthicknesses T2 of 1.0 millimeters. These dimensions are merelyillustrative. In general, branches 292 and 294 need not have the samedimensions, and the thickness of single branch 290 need not be twice thethicknesses of branches 292 and 294. Overlapping Y-junction 288 may be aseamless Y-junction. Fibers may run seamlessly along the length of cable236. Fibers that are in single branch 290 may pass through Y-junction299 and into one of either branches 292 and 294. The number of fibersthat are present in single branch 290 may be the sum of the number offibers in branches 292 and 294.

The ribbon-shaped cables of FIGS. 39 and 40 may have rectangular,oblong, or oval profiles. Examples of ribbon-shaped cables are shown inthe cross-sectional view of FIGS. 41A-41D. Each of the fiber-basedcables of FIG. 41A-41D has a width W that is greater than a thickness T.Cable 296 in FIG. 41A has a cross-section that that is substantiallyrectangular with sharp corners. Cable 298 in FIG. 41B has across-section that is substantially rectangular with rounded corners.Cable 298 may be said to have an oblong-shaped cross-section. Cable 300in FIG. 41C has a flattened oval-shaped cross-section. The cross-sectionof cable 302 in FIG. 41D is an oval that is rounder than that of cable300 in FIG. 41C.

Headphones 304 in FIG. 42 may have a fiber-based cable such as cable 320with a seamless Y-junction such as Y-junction 306. One side ofY-junction 306 may have a single branch 308 leading to an audioconnector 310 at the proximal end of cable 320. Another side ofY-junction 306 may have two branches 312 and 314, each leading to anearbud 316 at the distal portion of cable 320. Branch 312 may have auser interface such as a button assembly or other suitable input-outputcomponent. The input-output component may include one or moremicrophones, status indicators, buttons, switches, etc. With onesuitable arrangement, which is sometimes described herein as an example,branch 312 may be provided with a button controller assembly such asswitch-based controller 318. A user may use controller 318 to transmitinformation to an electronic device that is connected to audio connector310. For example, a user may actuate one of several differentbutton-based switches (e.g., a rewind or back button, a stoop or pausebutton, a forward or play button, etc.). A microphone in controller 318may be used to gather a user's voice (e.g., to serve as a voicemicrophone during a telephone call). Headphones 304 may also incorporatea microphone that is located at a location that is remote fromcontroller 316.

Fiber-base cable 320 of FIG. 42 may have a fiber-based sheath thatsurrounds insulated conductive wires. Headphones 304 may have wires thatconnect contacts (terminals) in audio connector 310 to each earbud 316to provide audio for a user. Headphones 304 may have, for example, twowires that run from audio connector 310 to each earbud 318. One of thewires of each pair of wires may serve as a common ground. The other wirein each pair may serve as either a left audio wire or a right audiowire, respectively. Additional wires may run from audio connector 310 tocontroller 318 to provide button and optional microphone functionality.For example, two insulated wires, or a two-conductor coaxial cable, maybe used to convey signals to and from controller 318. If a microphone isincorporated into headphones 304 (e.g., in connection with additionalcircuitry in controller 318), there may be additional conductive wiresthat transmit signals from the microphone to connector 310. If desired,the conductive wires may be intertwined with the fibers of fiber-basedheadphones 304.

When cable 320 is formed using a continuous process of the typedescribed in connection with FIG. 20 , the same number of fibers may bepresent at each end of cable 320. The number of fibers in branch 308 maybe the sum of the number of fibers in branches 312 and 314. The samenumber of insulated wires may also be present at each end of cable 320.For example, if six insulated wires are present in branch 308, then twoinsulated wires may be present in branch 314 and four insulated wiresmay be present along the entire length of branch 312. Wires that connectconnector 310 with controller 318 may continue upward on branch 312 toearbud 316, even though these wires are not needed to convey signalsbetween controller 318 and additional components in the vicinity ofearbud 316.

Conductive wires in a fiber-based cable need not be contained within afiber-based sheath. Conductive wires may, for example, be intertwineddirectly with other fibers. If desired, the relative position of theconductive wires among the other fibers in the cable may be varied byintertwining tool 14 as a function of position along the length of thecable. For example, the conductive wires may be located in the centralcore of the cable at some locations along the cable and may be locatedon the surface of the cable at other locations along the cable. Anarrangement of this type may be to connect contacts in audio connector310 to circuitry in controller 318.

An illustrative arrangement in which intertwining tool 14 adjusts therelative position of insulated wires within a fiber-based cable to allowthe wires to be interconnected to circuitry in controller 318 isillustrated in the examples of FIGS. 43A-43D.

A perspective view of a segment of fiber-based cable 322 is shown inFIG. 43A. Section 324 may be a region of cable 322 that forms terminalsfor an integral switch. In this type of arrangement, a switch may beformed from a pair of exposed wires, so it is not necessary to includecircuitry for implementing a more complex multi-function buttoncontroller for the headset. FIG. 43B-43D are cross-sectional views ofcable 322 taken along lines X-X, Y-Y, and Z-Z of cable 322.

FIG. 43B is a cross-sectional view of cable 322 at location X, which ison one side of switch region 324. Cable 322 of FIG. 43B has intertwinedfibers 332. Fibers 332 may be monofilament or multifilament fibers.Fibers 332 may be arranged in a sheath around insulated conductive wires247. Fibers 332 are shown in FIG. 43B as being arranged in a sheath witha thickness of two fiber layers. In general, fiber sheaths may have anysuitable thickness. Each insulated wire 247 has insulation 250surrounding a conductive center such as center 248. Four insulated wires247 are shown in FIG. 43B. In general, cable 322 may have any suitablenumber of insulated wires. Insulated wires 247 may be provided asindividual wires, as twisted pairs, as parts of coaxial cables, etc.

FIG. 43C is a cross-sectional view through line Y-Y of cable 322. InFIG. 43C, two of the wires 247 have been placed at the surface of cable322 by intertwining tool 14 and have been stripped of their insulationto form terminals 342 and 344. Two other wires 247 remain embedded inintertwined fibers 332.

During the fabrication of cable 322, intertwining machinery may be usedto ensure that the insulated wires are contained within the core regionof the cable (as in locations X and Z of cable segment 322 of FIG. 43A)in regions outside of switch region 324. This helps protect the wiresfrom damages (e.g., from scratches). The intertwining tool mayselectively bring the insulated wires to the surface of cable 322 atdesired locations such as location Y in FIG. 43C. After (or before)fiber-based cable 322 has been formed, insulated wires 247 may beselectively stripped of their insulations 250 at locations such aslocation Y, leaving their conductive centers 248 exposed on the surfaceof the cable. Terminals 342 and 344 may form a switch 324. Such a switch324 may be shorted together when touched by a user. For example,terminals 342 and 344 may be electrically connected to each other by theskin on a user's finger (finger 346) when the user's finger bridgesterminals 342 and 344. Terminals 342 and 344 may also be bridged by amechanical lever or other switching mechanism.

FIG. 43D is a cross-sectional view through fiber-based cable 322 atlocation Z. At location Z, insulated wires conductive wires 247 liewithin fibers 332 and insulation 250 is unstripped. Fibers 332 may forma fiber-based sheath surrounding insulated wires 247 or fibers 332 maybe intertwined with insulated wires 247.

FIG. 44A shows a fiber-based cable 354 that has a controller (e.g., acontroller such as controller 318 of FIG. 42 ). As shown in FIG. 44A,controller 345 may have a housing that surrounds portions of the cable.Controller 345 may be a switch, circuitry such as circuitry in aswitch-based button assembly with multiple buttons and an optionalmicrophone, or other suitable user interface circuitry (as examples).Controllers such as controller 334 may include circuitry for supportingcommunications with electronic devices over the wires of cable 354.Controller 345 may have one or more switched-based buttons, such asbutton 346. Cross-sectional views of cable 354 taken at locations X, Y,and Z are shown in FIGS. 44B, 44C, and 44D.

FIG. 44B is a cross-sectional view of cable 354 taken through line X-Xof FIG. 44A. Intertwined fibers 332 of FIG. 44B may be monofilament ormultifilament wires and may be formed from any suitable material.Insulated conductive wires 247 have insulation 250 surroundingconductive center 248. Four wires 247 are shown in FIG. 44B. In general,cable 354 may have any suitable number of wires. If desired, wires 247may also be provided in the form of coaxial cables. In FIG. 44B,intertwined fibers 332 are shown as surrounding insulated wires 247.

FIG. 44C is a cross-sectional view through controller 345 and associatedbutton 346 taken along line Y-Y of FIG. 44A. Two of the insulated wires247 have been positioned on the surface of cable 354 by intertwiningtool 14 and have been stripped of their insulations 250. This exposesconductive centers 248 of wires 247 and forms terminals 342 and 344.Terminal 342 may be connected by solder 348 to pad 352 of switch 346 orother circuitry in controller 345. Terminal 344 may be connected bysolder 350 to pad 654 of switch 346 or other circuitry in controller345. When button 346 is pressed by a user, terminals 342 and 344 may beelectrically connected (i.e., shorted together) closing the switch. Inother arrangements (e.g., arrangements in which controller 345 is formedfrom more complex circuitry), actuation of button 346 may result in thetransmission of communications signals over the wires connected toterminals 342 and 344. The use of a switch to form controller 345 ismerely illustrative.

FIG. 44D is a cross-sectional view of cable 354 taken through line Z-Zof FIG. 44A. As in FIG. 44B, insulated conductive wires 247 may beembedded within intertwined fibers 332 by intertwining tool 14. In thisregion of the cable, wires 247 typically have intact insulation 250(i.e., insulation that has not been stripped and therefore surroundsconductive centers 248).

During the formation of fiber-based cables such as the cable of FIG. 20, intertwining tool 14 of FIG. 1 may be used to bring insulated wires247 from within cable 354 (at location X), to the surface of cable 354(at location Y), and back inside cable 354 (at location Z). After cable354 is formed, insulation 250 may be stripped from wires 247 at locationY to form terminals 342 and 344. A switch or more complex input-outputcircuitry may then be connected to terminals 342 and 344. If desired,more than two wires may be stripped and connected to the input-outputcircuitry. For example, three or more wires may be stripped andconnected to switches or more complex circuitry within controllerassembly 345, four or more wires may be stripped and connected toswitches or more complex circuitry within controller 345, etc.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. A fabric case for an electronic device havinghousing corners, the fabric case comprising: a planar rear wall formedfrom a first set of fibers; sidewalls formed from a second set offibers; and curved corners between the sidewalls, wherein the curvedcorners have compound curves that are formed from three-dimensionallyknitted fibers, wherein the sidewalls and the curved corners haveC-shaped profiles and wherein the curved corners have non-uniform fiberspacing to conform to the housing corners of the electronic device. 2.The fabric case defined in claim 1 further comprising first and secondfabric regions, wherein the first fabric region has less binder and moreflexibility than the second fabric region.
 3. The fabric case defined inclaim 1 wherein a non-uniform fiber spacing of the curved corners isless than a fiber spacing between the fibers in the first set of fibers.4. The fabric case defined in claim 3 wherein the electronic device hasa front face with a display and has a rear face and wherein thesidewalls are configured to extend along four respective edges of thedisplay.
 5. The fabric case defined in claim 4 wherein the planar rearwall covers the rear face of the electronic device.
 6. The fabric casedefined in claim 4 wherein the housing corners of the electronic devicehave additional compound curves and wherein the curved corners of thefabric case conform to the additional compound curves of the electronicdevice.
 7. The fabric case defined in claim 4 wherein the electronicdevice has curved sidewalls and wherein the sidewalls of the fabric caseconform to the curved sidewalls of the electronic device.
 8. The fabriccase defined in claim 1 further comprising a fiber sheet that forms atleast part of the curved corners.
 9. The fabric case defined in claim 8wherein the fiber sheet has open gaps in the curved corners.
 10. Thefabric case defined in claim 9 wherein the three-dimensionally knittedfibers cover the open gaps.
 11. A fabric case for an electronic device,comprising: a rear wall; four sidewalls coupled to the rear wall,wherein the rear wall and the four sidewalls surround a cavity thatreceives the electronic device; and four corners interspersed with thefour sidewalls, wherein each corner of the four corners has compoundcurves formed from three-dimensionally knitted fibers and has a set ofopen gaps that allows the corner to conform to a respective compoundcurve of the electronic device.
 12. The fabric case defined in claim 11wherein the three-dimensionally knitted fibers cover the open gaps. 13.The fabric case defined in claim 11 wherein a first fiber spacing of thefour corners is greater than a second fiber spacing of the rear wall.14. The fabric case defined in claim 13 wherein the first fiber spacingis non-uniform across each of the four corners so that the four cornersconform to housing corners on the electronic device.
 15. The fabric casedefined in claim 14 wherein the four sidewalls have C-shaped profiles.16. A fabric case for an electronic device having housing corners, thefabric case comprising: a rear wall formed from first fibers; sidewallsextending from the rear wall; and curved corners having compound curvesformed from three-dimensionally knitted second fibers, wherein thecurved corners have a non-uniform fiber spacing that is greater than aspacing between the first fibers and that allows the curved corners toconform to the housing corners of the electronic device.
 17. The fabriccase defined in claim 16 wherein the first fibers comprise knit fibers.18. The fabric case defined in claim 16 wherein the electronic devicehas additional compound curves and wherein the curved corners conform tothe additional compound curves.
 19. The fabric case defined in claim 16wherein the sidewalls have C-shaped profiles.
 20. The fabric casedefined in claim 19 wherein the electronic device comprises curvedsidewalls and wherein the sidewalls of the fabric case conform to thecurved sidewalls.